Excerpt

IntroductionOver the past 20 years or so, the accuracy of the conventional Riva-Rocci/Korotkoff technique of blood pressure measurement has been questioned and efforts have been made to improve the technique with automated devices. In the same period, recognition of the phenomenon of white-coat hypertension, whereby some individuals with an apparent increase in blood pressure have normal, or reduced, blood pressures when measurement is repeated away from the medical environment, has focused attention on methods of measurement that provide profiles of blood pressure behaviour rather than relying on isolated measurements under circumstances that may in themselves influence the level of blood pressure recorded. These methodologies have included repeated measurements of blood pressure using the traditional technique, self-measurement of blood pressure in the home or work place, and ambulatory blood pressure measurement using innovative automated devices.Blood pressure measurement is the basis for the diagnosis, management, treatment, epidemiology and research of hypertension, and the decisions affecting these aspects of hypertension will be influenced for better or worse by the accuracy of the measurement. An accurate blood pressure reading is a prerequisite, therefore, regardless of which technique is used, yet all too often the accuracy of measurement is taken for granted or ignored.The purpose of this monograph is to serve as a reference source for other guidelines relating to hypertension and cardiovascular disease. The content is divided into four parts: Part I is devoted to issues common to all techniques of measurement, Part II to conventional blood pressure measurement (CBPM), Part III to ambulatory blood pressure measurement (ABPM) and Part IV to self blood pressure measurement (SBPM).Part I. Aspects of blood pressure measurement common to all techniquesFactors affecting the techniqueSelecting an accurate deviceAn accurate device is fundamental to all blood pressure measurement [1]; if the device used to measure blood pressure is inaccurate, attention to methodological detail is of little relevance. It is acknowledged that the accuracy of blood pressure measuring devices should not be based solely on claims from manufacturers, which can at times be somewhat extravagant. Instead, independent validation, with the results published in peer-reviewed journals, should be demanded [2]. However, manufacturers often ignore this recommendation and potential purchasers are generally unaware of this requirement, assuming – not unreasonably – that if a product reaches the market place, it will measure blood pressure accurately. Aware of this problem, the Association for the Advancement of Medical Instrumentation (AAMI) published standards for electronic and aneroid sphygmomanometers in 1987, which included a protocol for the evaluation of the accuracy of devices [3], and this was followed in 1990 by the protocol of the British Hypertension Society (BHS) [4]; both protocols were revised in 1993 [5,6]. These protocols, which differed in detail, had a common objective, namely the standardization of validation procedures to establish minimum standards of accuracy and performance, and to facilitate comparison of one device with another. A large number of blood pressure measuring devices have been evaluated according to one or both protocols [2]. On the basis of past experience, it is evident that the conditions demanded by the protocols are difficult to fulfil. As a result, the Working Group on Blood Pressure Monitoring of the European Society of Hypertension (ESH) has recently published a simplified protocol to facilitate the evaluation process, with the expectation that manufacturers will be more likely to submit their products for validation in order to obtain the minimum approval necessary for a device to be used in clinical practice.